Table of Contents
Advertisement
•
At extremes, can cause the boat to porpoise
Shifting weight to front (bow):
•
Improves ease of planing
•
Improves rough water ride
•
At extremes, can cause the boat to veer back and forth (bow steer)
BOTTOM OF BOAT
For maximum speed, a boat bottom should be nearly a flat plane where it
contacts the water and particularly straight and smooth in fore and aft direction.
•
Hook: Exists when bottom is concave in fore and aft direction when
viewed from the side. When boat is planing, hook causes more lift on
bottom near transom and allows bow to drop, thus greatly increasing
wetted surface and reducing boat speed. Hook frequently is caused by
supporting boat too far ahead of transom while hauling on a trailer or
during storage.
•
Rocker: The reverse of hook and much less common. Rocker exists if
bottom is convex in fore and aft direction when viewed from the side, and
boat has strong tendency to porpoise.
•
Surface roughness: Moss, barnacles, etc., on boat or corrosion of
outboard's gear housing increase skin friction and cause speed loss.
Clean surfaces when necessary.
WATER ABSORPTION
It is imperative that all through‑the‑hull fasteners be coated with a quality
marine sealer at time of installation. Water intrusion into the transom core
and/or inner hull will result in additional boat weight (reduced boat
performance), hull decay, and eventual structural failure.
CAVITATION
Cavitation occurs when water flow cannot follow the contour of a fast‑moving
underwater object, such as a gear housing or a propeller. Cavitation increases
propeller speed while reducing boat speed. Cavitation can seriously erode the
surface of the gear housing or the propeller. Common causes of cavitation are:
•
Weeds or other debris snagged on the propeller
•
Bent propeller blade
•
Raised burrs or sharp edges on the propeller
ELEVATION AND CLIMATE
Elevation and climate changes will affect the performance of your power
package. Loss of performance can be caused by:
•
Higher elevations
•
Higher temperatures
•
Low barometric pressures
GENERAL INFORMATION
14
eng
Hide quick links:
Advertisement
Table of Contents
